CJ alternator

[jay79cj7]

2 Quick questions:
1) What does the small gauge brown wire coming off the alternator back to the fuse box do? I have seen aftermarket "high output" alternators that are "1-wire" and thus do not use this wire. I am wondering what I would be disconnecting.
2) I am still looking into a higher output alternator to keep up with my TFI and future Blazer motor. What amp are you guys with similar combinations running?
Thanks!

 

[nana]

to question 1) the brown wire provides the field current (positive) for the altenator. The voltage reguator, which is inside the alternator controls this field current such as the output voltage is constant and independent from the RPM. The higher this current at a fix RPM the higher the output voltage. Ususally the brown cable gets 12V from the battery when you turn on the ignition key. If you cut it the alternator will not charge the battery anymore

femtocam.

 

[BakedAlaskan]

Engine Swap 6 cyl. to 8

I currently have the Holly Projection on my CJ and misc lights and stuff and haven't noticed any problems with the charging system yet. But knowing I plan on adding more high watt goodies I know I will need an upgrade too. Since most of Jeeps bolt ons are GM products shouldn't there be a GM alternator off a rig that bolts up and has a better output?? Similar to the heater motor upgrade?? Have you found anything yet in your search??

 

[jay79cj7]

There are some high output's on ebay... 135, 160 and 180 amp. They say they produce good current at idle, but White says he has one and it doesn't kick in until around 1500 rpms. There is the JCW rebuild kit that Bounty Hunter likes, but it says right on the site that it will reduce output at idle. With headlights, fogs, heater, stereo, TFI, my jeep doesn't like stoplights. I want to find something that has good low rpm output because I don't want to have to turn off the heater and fog lights at every stoplight. Mean Green's are supposed to be good, but cost alot more than anything else out there, and I am cheap. I guess it could be that my stock alt is just tired, but I figure that if I am going to replace it I am going to upgrade. I will keep looking. If anybody has had a good experience with an upgrade, please let me and BakedAlaskan know.

 

[redrooster]

Don't quote me on this but I think the Vortec Chevy alternators are 140 amp. They aren't cheap either though.

 

[southtj]

Through my job, I am able to get my hands on a large number of factory Ford 130amp alternators. We take them off of vans and put the 200amp alts on so we have boxes of 130s sitting around. I'm sure we'd let them go pretty cheap if they would work. I'm sure the brackets would need a bit of modifications. Probably only puts out about 30-40 at idle though.

 

[BakedAlaskan]

I would think since most of these are set up for higher rpm engines you could get a smaller pulley and gain better idle output without distroying it at max rpm. We all know the "Scarry high 4200rpm" of the 258 ain't going to blow much up. And 30-40amp output can't be worse then our weak 63 amp at max stock alternators, right?? All just a guess.

Any thoughts?? I would think the bracket and wiring would be fairly easy.(I hope :wink: )

 

[chinard]

Since most of Jeeps bolt ons are GM products shouldn't there be a GM alternator off a rig that bolts up and has a better output?? Similar to the heater motor upgrade?? Have you found anything yet in your search??

Okay, if we are talking about CJ's that use the old style delco alternators then alternator swaps are super easy.
When my original alternator died (bearings went) i swapped in an alternator from my neighbour's GMC sierra and it worked like a charm.
Of course that alternator didnt have much output so i had to splurge and get myself a new 150amp powermaster and i've never dropped below 13.5 volts even with everything turned on at the same time. (high beams, fog lights, heater blower on full, wipers, stereo, intereor lights, plus laptop plugged into my power inverter)

Also, like mentioned before, most of these alternator makers consider "idle speed" to be about 1500 rpm, and consider "highway speed" to be around 6000 rpm, so even with a high powered alternator, you will not be getting anywhere near the rated amperage.

I've heard alot of people are happy with the rebuild kits. Alternators are pretty easy to take apart and mess with.. no rocket science here. Some people dont trust em... Whatever

As far as what the brown wire does, i was always under the impression that was to supply a regulated 12v feed to your fuse box for distribution to the rest of your electrical system. I've disconnected it before while the engine was running and havent seen much of a drop in power, so who knows... I just go by what the diagrams and the voices in my head tell me :roll: